The world’s oceans are warming four times faster than they were in the late 1980s, according to a new study. The alarming acceleration helps explain why 2023 and 2024 saw unprecedented ocean temperatures — and more extreme storms.

The findings have enormous ramifications for ocean health, as rising temperatures impact everything from coral reefs to fisheries. The longer-term knock-on impacts are even more concerning, including higher sea levels, more extreme storms, and more frequent and severe fires, said Christopher Merchant, lead author of the study, which was published in Environmental Research Letters on Tuesday.

"With climate change, it’s the oceans that set the pace,” said Merchant, an ocean and Earth observation scientist at the University of Reading. The new research shows ocean temperatures in the next 20 years could rise more than in the past 40 years "by a significant margin.” Unless meaningful steps are taken to cut emissions and wind down fossil fuel use, Merchant said, "I expect that the climate change that’s coming will be at the high end of what climate modelers have been telling us.”

Temperature records set in 2023, and then beaten in 2024, caught scientists off guard. Last year, the ocean hit a heat record that was 0.6 Celsius (1.1 Fahrenheit) above the 1981 to 2010 average. (The global average temperature was even higher due to land heating faster.)

While the world was in the grips of El Nino, a natural warming phenomenon in the tropical Pacific, the heat anomalies seen globally were seemingly too large to be explained by that alone. Human-caused climate change intuitively seemed part of the explanation, and the new study is one of the first lines of hard evidence linking the recent acceleration in global warming to burning fossil fuels, said Kim Cobb, director of the Institute at Brown for Environment and Society.

Understanding the "true damages of continued fossil fuel emissions” and the cost to society is of the utmost importance, she said. "This paper would suggest that they’re worse than we previously thought.”

The paper looked at two datasets, one looking at sea surface temperatures and another tracking the Earth’s energy imbalance, which occurs when more energy from the sun is absorbed by land and water than escapes back into space.

After accounting for natural year-to-year variability, the study showed these phenomena move together over the long term. Ocean temperatures are now rising at a rate of 0.27 C per decade, compared to 0.06 C 40 years ago. That acceleration is fueled by an increase in the Earth’s energy balance, which has roughly doubled since 2010 as greenhouse gas concentrations have increased and disappearing ice has meant less sunlight is reflected back into space, the study concluded.

"If you extrapolate their accelerated warming rates into the next couple decades, you actually exceed what our climate models would be giving us for even the strongest pathway of fossil fuel reductions,” Cobb said.

Global ocean temperatures hit record highs for 450 days straight between 2023 and early 2024, which helped fuel massive hurricanes. While some of this warmth came from El Nino, the study showed that 44% of the record warmth was caused by oceans absorbing heat at a faster rate.

Warmer oceans feed other worrying global changes as well. Polar ice is melting faster than previously thought and contributing to sea level rise as hot seas undercut the glaciers keeping it trapped on land. Other types of destructive weather are also getting an assist: As the planet warms, land-based consequences, like this season’s devastating fires in California, also become more frequent, Cobb noted.

"That’s really the full impact of a paper like this,” she said. "We’re talking about accelerating these kinds of hellish episodes, not just here in America but globally.”

The world's ability to meet its climate goals was already in question before U.S. President Donald Trump took office. But those efforts are in even more doubt as he signed executive orders to increase fossil fuel production and halt leases for offshore wind projects on federal land during his first week in office. He has also lamented the cost of laws aimed at reducing greenhouse gas emissions, such as the Inflation Reduction Act, and froze some funding.

"People are balking at the cost of cutting down our carbon emissions,” Merchant said. "Although it’s not free, it is a bargain because in the long run, not doing it is more expensive.”